14 METEOROLOGY. 



the greater coolness of the summers, Indian corn, except as a green vegetable, does not 

 generally succeed, and perhaps a few other products of California may be found unprofitable, 

 but for others, especially orchard fruits, that State is surpassed. 



GENERAL CONCLUSIONS. 



The favorable conclusions as to the climate of the country in the route of the expedition, 

 stated in the first report, have been fully sustained by more recent observations. 



As shown by the accounts of all who have traversed the Rocky mountains, during almost 

 every winter month the snow there met with would not present the slightest impediment to the 

 constant passage of railroad trains. And, in regard to temperature, the whole of these mountains 

 between Fort Benton and Bitter Root valley, a distance in a straight line of 190 miles, have a 

 milder winter climate than Wisconsin or Iowa, or any part of Nebraska east of the 100th 

 meridian. A mean temperature of 20° to 25° must j^revail throughout, excepting about five 

 miles of the dividing ridge, which, rising 2,500 feet above the Bitter Root valley, and 3,400 

 above Port Benton, will, by the rule already stated, fall to a mean of 16°; though from its very 

 narrow extent, and the almost constant influence of the west winds, it must usually approach 

 nearer the climate of Bitter Root valley, or have a mean of 19.50. Even when crossed by 

 Lieutenant Grover, while the cold northeast wind was blowing, we find that its temperature 

 was more than a degree higher than it should have been when compared with Fort Benton. 



From the increasing altitude and width of the Rocky mountain plateau, towards the south 

 we find that the length of country, having a climate of similar coldness, must be much greater, 

 as traversed by any line of railroad between this and that of the 35th parallel; while there, the 

 distance from the mild winds of the Pacific coast, and the local influences of a much greater 

 extent of snowy mountains, must still further decrease the mean winter temperature. The 

 increased mildness of winter, due to a more southern latitude, is more than compensated by 

 the greater altitude of any pass between the two routes; while the same fact is to be seen in 

 relation to any interval of the same length (190 miles) traversed by the routes through those 

 passes. 



Of the relations of climate to the agricultural capacities of the country on the route, enough 

 has been given to show that, while inferior to many parts of the United States in its adaptation 

 for great variety of crops, it compares favorably with the best portions of the empire of Russia 

 for the cultivation of the great staples of agriculture, and west of the Rocky mountains far 

 surpasses them, approaching the most productive countries of Europe in character. Compared 

 with any other route north of the 30th parallel, the climate is superior for agriculture. The 

 natural growth of trees among the mountains, on this route alone, proves the superiority of 

 climate over that of the elevated portions of the central Rocky mountains, where there is not 

 suflBcient moisture to sustain them, except at a higher elevation, varying from 5,000 to 8,000 

 feet. There is nothing in the soil of any portion, except the western part of the great plain 

 of the Columbia, which forbids agriculture; and, allowing for mountains, also, the distance 

 traversed through lands, not cultivable continuously, will not exceed 320 as a maximum, most of 

 which is grazing land, and contains patches of arable land suflScient for a stock-raising 

 population, and for nuclei for mail and railroad stations. 



